Various methods are known in the art for optical 3D mapping, i.e., generating a 3D profile of the surface of an object by processing light reflected from the object. This sort of 3D profile is also referred to as a 3D map, 3D image, depth map or depth image, and 3D mapping is also referred to as depth mapping. The term “light,” as used in the context of the present description and in the claims, refers to optical radiation in any of the visible, infrared, and ultraviolet ranges.
U.S. Patent Application Publication 2011/0279648, for example, describes a method for constructing a 3D representation of a subject, which comprises capturing, with a camera, a 2D image of the subject. The method further comprises scanning a modulated illumination beam over the subject to illuminate, one at a time, a plurality of target regions of the subject, and measuring a modulation aspect of light from the illumination beam reflected from each of the target regions. A moving-mirror beam scanner is used to scan the illumination beam, and a photodetector is used to measure the modulation aspect. The method further comprises computing a depth aspect based on the modulation aspect measured for each of the target regions, and associating the depth aspect with a corresponding pixel of the 2D image.
As another example, U.S. Patent Application Publication 2013/0207970 describes mapping apparatus that includes a transmitter, which emits a beam comprising pulses of light, and a scanner, which is configured to scan the beam, within a predefined scan range, over a scene. A receiver receives the light reflected from the scene and to generate an output indicative of a time of flight of the pulses to and from points in the scene. A processor is coupled to control the scanner so as to cause the beam to scan over a selected window within the scan range and to process the output of the receiver so as to generate a 3D map of a part of the scene that is within the selected window.